Do you have a hard time remembering which team of pets you used to defeat the Pandaren Spirit Tamers? Or any other pet tamer or the new elite wild pets for that matter? Rematch can save teams on a per-target basis. Meaning you can save a team of pets to use against the Thundering Pandaren Spirit, a team for Aki the Chosen, a team for Gorespine, etc. Once you have your team, save it and don't waste any more time experimenting the next time you battle.